1. Field of the Invention
The present invention generally relates to a leaf spring and a suspension system employing a leaf spring for use in a vehicle. This disclosure presents several example embodiments that may be utilized for particular purposes.
2. Discussion of the Prior Art
Wheeled vehicles commonly have suspension systems that utilize springs to suspend a body assembly above the axles to which wheels are rotatably connected. In this context, the body assembly generally is referred to as the sprung portion of the vehicle and the wheels and respective axles, whether dealing with independent suspensions or solid axle suspensions, generally are referred to as the unsprung portions of the vehicle. For ease of reference, suspension systems may be said to be part of a chassis of a vehicle with an understanding that the chassis may include a frame assembly or may be integrally constructed with a body assembly, such as in a so-called unibody construction.
Suspension systems typically include active components designed to isolate from the sprung portion the disturbances encountered by the unsprung portions, such as occur during acceleration and deceleration, or during jounce and rebound of the axle when traversing bumps in a road surface and the like, and to withstand lateral and roll oriented forces, such as are encountered when cornering. Such systems also typically are designed with an intended relative positioning of the unsprung portions to the sprung portion at rest and during normal operation of the vehicle when being driven. This relative positioning results in what is commonly referred to as the ride height of a vehicle. Thus, the normal ride height of a vehicle relates to the height of the vehicle when it is ready to be driven with the suspension system in a normal condition to isolate disturbances.
With the advent of new laws regarding braking capabilities of vehicles, such as heavy duty trucks, forces and stresses experienced in suspension systems during hard braking are creating more extreme conditions for suspension systems. To meet the new braking requirements, suspension systems using traditional leaf spring configurations that tend to have equal length in the front and rear limbs would likely have a relatively long, thick and inactive axle seat portion, and sufficient spring thickness and vertical spring rate to be capable of dealing with the resulting axle wind up, and with sufficient roll stiffness. However, such a configuration with a massive axle seat portion, substantial thickness and a relatively high spring rate within the limbs of the leaf spring results in heavy springs that also produce relatively harsh ride quality.
The present disclosure addresses shortcomings found in prior art suspension systems.